An option to preserve empty lines between logical blocks

[breki]

Description

I tend to add empty lines between logical blocks of code inside functions so the code is more legible (it's a matter of taste, I know, but I imagine I'm not the only one doing this). Unfortunately Fantomas removes these empty lines (and using PreserveEndOfLine is an overkill).

Repro code

Example code:

    let runValidator (validator: ResultFunc<'Input,'Output,'TError>) input =
        let validatorResult = validator input
        match validatorResult with
        | Error error -> 
            anyErrors <- true
            collectedErrors <- error :: collectedErrors
        | Ok output ->
            collectedOutputs <- output :: collectedOutputs

    funcs 
    |> Seq.iter(fun validator -> runValidator validator input)

    match anyErrors with
    | true -> Error collectedErrors
    | false -> Ok collectedOutputs

gets formatted to

    let runValidator (validator : ResultFunc<'Input, 'Output, 'TError>) input =
        let validatorResult = validator input
        match validatorResult with
        | Error error ->
            anyErrors <- true
            collectedErrors <- error :: collectedErrors
        | Ok output -> collectedOutputs <- output :: collectedOutputs
    funcs |> Seq.iter (fun validator -> runValidator validator input)
    match anyErrors with
    | true -> Error collectedErrors
    | false -> Ok collectedOutputs

[jindraivanek]

Fantomas 3.0 keeps empty newlines by default: link.

Please re-open if you find another problematic case.